Snow horn



Feb. 3, 1970' W. B. STANFORD, JR

SNOW HORN Filed July 28, 1967 WATER IN WALLACE B STANFORD,JR 62 mun/r09 WALLACE BRI /5E S MNF 0190 ,JR.

A TTOENEV United States Patent M US. Cl. 6236 8 Claims ABSTRACT OF THE DISCLOSURE Pre-cooled liquid carbon dioxide, CO is expanded to form a pressurized mixture of CO snow and CO vapor at the throat of a conical snow horn the mouth of which opens downward; the horn being surrounded by an inner tube spaced from the horn and open top and bottom; the said assembly being enclosed in a heat insulating outer tube closed at the top, the enclosure defined between said inner and outer tubes communicating with the space between the inner tube and born at top and bottom; said outer tube extending below the lower end of the inner tube; the arrangement enabling aspiration of vapor by the stream of vapor emerging from the horn, said aspiration causing circulation of vapor in a loop path downward between horn and inner tube and upward between inner and outer tubes; a coil surrounding the inner tube for pre-cooling incoming liquid CO and a ring nozzle at the bottom edge of the outer tube for spraying fluid upon the CO snow falling from the mouth of the inner tube.

BACKGROUND OF INVENTION Field of the invention The invention relates to an improved method and apparatus for producing carbon dioxide in snow form from liquid carbon dioxide and combining said snow with water or other fluid.

Description of the prior art Prior art devices for producing carbon dioxide in snow form have often been relatively complex and excessively heavy, particularly so as to be entirely unsuitable for use in aircraft or spacecraft. In particular, they have included heavy and bulky heat exchangers and/or compressors for conserving refrigeration and for recompressing the vapor which generally forms concurrently with the formation of the solid state carbon dioxide, prior art models weighing 40 pounds or more. Prior art devices have generally been restricted to certain flow rates and to end products of invariable consistency. They have been designed for use with a particular type of pressure source, for example bulk CO cylinder CO or converter C0 The operation has generally been affected by change of pressure with altitude. Furthermore, the operation has generally been carried out in a pressurized vessel, or has employed a high pressure compressor, introducing hazardous and expensive components.

SUMMARY OF INVENTION The invention constitutes an improvement over the prior art devices in that it has been found to be efficient, dependable and flexible. Apparatus in accordance with the invention can weigh as little as about 8 pounds. Flow rate and consistency of end product can be varied to meet demands with respect to proportional amounts of water and of carbon dioxide. The process can be adapted to use any available source of pressurized liquid carbon dioxide, bulk, cylinder or converter. The process is operable at any altitude and does not require electric power. Furthermore,

Patented Feb. 3, 1970 it does not have the hazardous characteristics inherent in the use of a pressurized vessel.

The invention provides a unique way to mix Water or other fluid with carbon dioxide snow. The resulting product can be used for food and plant preservation and freezing and in many other ways, for example, product mixtures of CO and water can be used advantageously mixed with mud as a lubricant for drill bits, as in drilling oil wells.

The invention can be used to make ice in areas where natural ice is not available. It can also be used for fire fighting.

Fluids other than water may be added to the carbon dioxide snow. For example, fluids containing milk, spices, sugar, fiavorings, etc., may be added to produce the desired product.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view, partly in section, and partly schematic, of an embodiment of the invention;

FIG. 2 is a cross-sectional view of the apparatus shown in FIG. 1, taken as indicated by the line 2-2 in FIG. 1; and

FIG. 3 is a cross-sectional view of the apparatus shown in FIG. 1, taken as indciated by the line 33 in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a frusto-conical born 20 opening downward is connected through a conduit 22 with a pressure-reducing valve 24, electro-mechanically controllable by means of a solenoid 26. The conduit 22 and horn 2.0 are centrally supported in a stepped cap 28. The lower step portion 30 of the cap 28 supports a heat conductive inner tube 32, preferably metal, which tube may be attached to the step 30 by friction fit, brazing, or other suitable joining, or the tube 32 may be integral with the cap 28. The tube 32 surrounds the lower major portion of the horn 20 and extends below the mouth of the horn 20 a considerable distance, e.g. an amount about equal to the length of the horn. An outer tube 34 lined with heat insulating material surrounds the inner tube 32 and is fastened to the upper step 36 of the cap 28 in any suitable manner to close the top of the tube 34, e.g. by a friction fit between the tube 34 and the upper step 36, or by adhesive, etc. The cap 28 is provided with an annular joining member 38 having a plurality of openings 40 which latter provide passages connecting a passage 56 between the outer tube 34 and inner tube 32 With a passage 54 betwen the inner tube 32 and the horn 20.

A coiled conduit 41, preferably of heat conductive material, is wound about the exterior of the inner tube 32, preferably in thermal contact with the tube 32. An inlet conduit 42 for the coil 41 extends from bottom to top of the coil and an outlet conduit 44 connects the coil with a water intake 50. To provide a very fine water mist, forming tube 46 with jets 48 directed inwardly and downwardly is mounted at the bottom of the outer tube 34, with a water intake 50. To provide a very fine water mist, I have used as many as jets formed by holes inch in diameter uniformly spaced around the tube 46.

To prevent the tube 46 or manifold from freezing from contact with the CO snow, the tube 46 is offset, as shown, as by being tangent with the outer surface of the tube 34, so that the falling snow does not touch the tube 46.

The conduits 22, 42 and 44 pass through the top member 52 of the cap 28 through respective openings which are hushed or otherwise sealed to maintain the cap 28 gas-tight at the top. The conduits 42 and 44 pass through 3 openings 40 in the partition 38 while permitting vapor to pass freely through the openings 40.

In the operation of the arrangement shown in FIGS. 1-3, liquid CO is supplied to the inlet conduit 42, conveniently at about degree Fahrenheit, which is accompanied by vapor pressure of about 21 atmospheres. No additional pressure is required in the operation to be described. The liquid from the conduit 42 is pre-cooled in the coil 41 by indirect heat exchange with cold vapor on both sides of the wall of the inner tube 32 and passes through the conduit 44 to the valve 24 at about -50 F.

Valve 24 may be operated manually or by a conventional solenoid 26. When the valve is opened, liquid CO flows through the valve and evolves into a mixture of solid particles of CO commonly called CO snow, and accompanying CO vapor. The particles composing the CO snow fall through and out of the horn 20, through the inner tube 32 and outer tube 34 below which latter the product CO snow may be collected or utilized in any desired manner.

In emerging under pressure from the mouth of the horn 20, the stream of vapor serves to aspirate other vapor from the space '54 between the horn 20 and the inner tube 32, causing a lowering of pressure in the space 54. Because the space 54 is connected to the space 56 by way of the openings 40, the vapor in space 56 is drawn upwardly and passes through openings 40. Some of the vapor from the main stream emerging from the mouth of the inner tube 32 is therefore directed into the space 56. There is thus established a circulation of CO vapor upwardly in passage 56, through the openings 40, downwardly in the passage 54 and along the inner wall of the tube 32 to the mouth of that tube, as indicated by arrows 58.

The inertia of the relatively dense cloud of falling snow within the tube 34 below the mouth of the tube 32 aids the suction at the mouth of the tube 32 in turning back the descending vapor within the tube 32 and redirecting it upward into the passage 56.

The passage 54 narrows toward the bottom due to the relative shapes of the horn 20 and tube 32, forming a Venturi-type annular passage. The circulating vapor in the path marked by the arrows 58 is sucked through the narrowing passage 54 and then passes into the wider passage constituted by the interior of the inner tube 32.

This recirculation of vapor greatly assists in the subcooling of the liquid passing through conduit 42. In addition, the downwardly moving annular layer of vapor coming from passage 54 assists in directing the snow downwardly.

Optionally, sub-cooling of the incoming liquid CO in the coil 40 may be supplemented or replaced by introducing liquid nitrogen into the passage 56 is by one or more jets 60, suitably located, as for example, around the circumference of the outer tube 34 at a height about the middle of the length of the inner tube 32. For simplicity in the drawing, only one such jet 60 is shown.

To coat the individual particles of CO snow with water ice, water may be supplied to the water intake 50 to provide inwardly and downwardly directed jets of water as indicated at 62 to form a fine mist. The CO particles traverse the region of the mist and accumulate a coating of water ice. In practice I have found that a downward angle of the jets about 45 degrees is advantageous although other angles can be used. The invention may be practiced with or without this water icing feature. The water is supplied to the intake 50 with a pressure preferably about 50 pounds per square inch. The resulting product so treated is a slow release carbonated water ice.

As stated above, fluids other than water may be forced into intake 50 for intermixing with the falling snow.

The flow rate and consistency of the product snow can be varied as desired, to meet demand, by varying the p s u e du tion and resu tant re ease rate of the qu d CO at the valve 24, as by means of the solenoid 26, and by supplying liquid CO and water in desired proportions.

In an embodiment which I have successfully operated, I have used an outer tube 34 thirty inches long and five inches in diameter; an inner tube 32, 19 /2 inches long and 3 inches in diameter; and a snow horn 20, 10% inches long, flairing from 1% inch diameter at the small end to 2% inch diameter at the large end; together with a coil 40 of 10 /2 turns. Using this embodiment, I have produced CO snow at the rate of three pounds three ounces per minute, obtaining approximately one pound of snow for two pounds of CO liquid processed.

With regard to the utility of the invention in the preservation of foods, it will be evident that the invention is not limited to use in the freezing of foods. The invention provides a slow, controlled release of refrigeration and of CO atmosphere for controlling a comprehensive climatic environment.

The varied characteristics of the product make it applicable to the preservation, packing and shipping of food products that require a combined low temperature and inerting effect. Several examples will be given: (1) in the packing and shipping of chickens which require two separate treatments, one with CO and the second with water ice, made practical without use of two separate products, and (2) in the grinding of meats where the current practice is to add CO in -Dry Ice form for cooling effect and water to add the required moisture.

Other examples in the food field include (3) the shipping of strawberries in rail cars requiring both water ice and solid CO as bunker ice; (4) shipment of certain leafy vegetables for which direct contact with solid CO causes spoilage; and (5) in the fishing boat industry at sea where brine solutions are now used.

In the floral industry, the invention is particularly applicable to shipment of roses, carnations, orchids, etc., now shipped with water ice, which would be improved by the action of CO in precluding oxygen, and would also reduce the weight factor important in air shipment.

The invention is useful in the well drilling field, both for water and oil wells, where mud is customarily used to lubricate the drill bit. By adding the product mixture of CO and water to the mud, the temperature of the mud during drilling is reduced. This in turn reduces the temperature of the drill, lowering the rate of necessary replacement of expensive diamond drill bits and saving time in pulling well casings.

The invention is also useful in the production of ice where other sources of ice are not available.

While illustrative forms of apparatus and methods in accordance with the invention have been described and shown herein, it will be understood that numerous changes may be made without departing from the general principles and scope of the invention.

What is claimed is:

1. Snow-forming apparatus comprising, in combination, a generally cylindrical chamber, a frusto-conical snow-horn mounted in said chamber, a cylindrical tube mounted in said chamber concentric with said horn and surrounding the same, said cylindrical tube being shorter in length than said cylindrical chamber and being substantially open at both ends to allow vapor to pass therethrough, conduit means wound on the exterior of said cylindrical tube for circulating carbon dioxide liquid in said chamber, said conduit means connected with expansion means, said expansion means being mounted at the small end of said horn for introducing said liquid under pressure into said horn, first passage means constituted by the proximity of said cylindrical tube and said horn, second passage means between said cylindrical tube and said cylindrical chamber, the vapor evolved from the expansion of said liquid passing through the open end of said cylindrical tube remote from the expansion means and then passing through said second passage means into a d firs p s ge mean the flow in said first assage means being in the same direction as the flow in said snow horn.

2. Apparatus in accordance with claim 1, in which the said liquid upon said expansion into said horn evolves as a mixture of vapor and of particles in the solid state, said solid particles passing through said horn and said cylindrical tube, and in which said generally cylindrical chamber is open at the bottom to allow said particles to leave the said chamber.

3. Snow-forming apparatus comprising, in combination, a generally cylindrical chamber, a frusto-conical snow horn mounted in said chamber, a cylindrical tube mounted in said chamber concentric with said horn and surrounding the same, expansion means for CO liquid, said means being mounted at the small end of said horn for introducing said liquid under pressure into said horn to form solid particles of snow and vapor, passage means constituted by the proximity of said cylindrical tube and said horn for allowing vapor evolved within said horn to pass between said horn and said cylindrical tube, together with means to produce a water mist in surrounding relationship to and at an end of said generally cylindrical chamber whereby as the said solid particles leave the generally cylindrical chamber they are coated with the water mist.

4. A snow-forming apparatus comprising, a housing defining a chamber, a snow horn having an open end and a closed end mounted in said chamber, conduit means for circulating carbon dioxide liquid in said chamber and then directing it through a port in the closed end of said horn for expansion to form gas and snow which passes out of the open end of said horn, manifold means having a plurality of perforations positioned in close proximity and in surrounding relationship to the snow discharged from the horn but in non-contacting relationship with the snow which is generated in said snow horn, said perforations being arranged to direct a plurality of jets into the passing snow.

5. The apparatus recited in claim 4 together with means for directing fluid into said manifold means.

6. The apparatus recited in claim 5 in which said fluid is water.

7. Apparatus for forming carbonated ice comprising a chamber, expansion means in said chamber for expanding carbon dioxide liquid to form snow and vapor, means to supply carbon dioxide liquid to said expansion means, means partially confining the carbon dioxide snow from the expansion means to direct said snow through a partially confined region, annular conduit means located outside of said region so that said snow is projected through the annular conduit means without contacting said conduit means, said conduit means having a plurality of orifices adapted to direct a spray of fluid inwardly into said region, and means to direct fluid into said annular conduit means.

8. The apparatus defined in claim 7 in which said fluid is water.

References Cited UNITED STATES PATENTS 1,546,682 7/1925 Slate 62-10 1,927,175 9/1933 Josephson 6210 2,016,815 10/1935 Gilmore 6235 XR 2,570,074 10/1951 Rupp 62-10 1,969,703 8/1934 Cribb et a1. 62-10 1,976,204 10/ 1934 Voorhees et a1. 6258 2,047,099 7/ 1936 Goosmann 62-10 3,208,935 9/1965 Nesbitt 23-150 FOREIGN PATENTS 1,144,283 2/ 1963 Germany.

304,958 1/ 1929 Great Britain.

642,057 8/ 1928 France.

890,062 2/ 1962 Great Britain.

NORMAN YUDKOFF, Primary Examiner US. Cl. X.R. 6210, 35, 347

P0405? UNITED STATES PATENT OFFECE (5/69) q q x CERTIFlCATh OF CORRECHON Patent No. 3,492,829 Dated February 3, 1970 Inventor) WALLACE B. STANFORD, JR.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 51, "betw en" should. read --between--.

2 line 56, after "coil" (second occurrence) should be inserted "M1 to the inlet side of the valve 24. An

- annular mist forming tube 46 with Jets &8 directed inwardly and downwardly is mounted at the bottom of the outer tube 3 4,.

lines 57, 58 and 59 should be cancelled.

Column 3 line 53, "is" should read --as--.

SIGNED AND SEALED JUN 3 0 1970 (S .Aueat:

F wmmrm E: samrmm, .m. Attestmg Officer Commissioner of Patents 

